Accurately determining the absolute wavelength of a single mode laser signal has many potential applications in many fields, including spectroscopy, communication system, and wavelength tunable lasers. Conventionally, wavelength locking and monitoring has been achieved used various components, including calibrated etalon filters, gratings, and arrays of color filters. Unfortunately, all of the conventional systems offer fairly bulky solutions that require complicated controls and assembly. Furthermore, some of these devices reflect a significant amount of light back to the light source that can potentially disturb laser sources, which further necessitates the use of bulky isolators. Conventional wavelength lockers and monitors that provide fine resolutions, e.g. 1 GHz or 10 pm of accuracy, typically require large footprints.
An object of the present invention is to overcome the shortcomings of the prior art by providing an integrated wavelength locker with low reflectivity and high resolution.